We Get More Calories From Roasted Peanuts Than Raw Peanuts

Peanuts are on average 50% fat, much of which is not digested when eaten raw. Source: Medical News Today

I recently posted a study about almonds, how an ounce of raw whole almonds may contain 14 grams of fat, but only 1 gram of that fat (8.5%) is freed for absorption by chewing. You could almost consider whole almonds a low-fat food.

This next study found that cooking liberates fat in a manner similar to chewing or grinding, maybe better:

The lipid-rich food here was peanuts. Researchers fed mice one of four diets that included peanuts: raw and whole, raw and blended, roasted and whole, and roasted and blended.

The two on the right, the roasted ones, provided a lot more fat and calories than the two on the left:

Our findings indicate that cooking increases the fraction of lipid available and the net energy gained from peanuts.

Mice that ate the roasted peanuts weighed significantly more than mice that ate the raw peanuts. The raw-eaters excreted more fat in their feces. Out it went. Even though they chewed the nuts well. In fact, the mice chewed so well that the authors surmise the whole nuts “were effectively blended upon reaching the stomach and small intestine.”

The same cannot be said for humans:

Prior studies have noted that human subjects given peanut butter (peanuts that have been roasted, and then ground) excreted less fat than those given whole roasted peanuts. This implies that mechanical processing of cooked peanuts increases the digestibility of their lipid, and presumably the energy gained from them.

So … raw almonds provide such little fat they could be considered part of a weight-loss plan, but peanut butter provides so much fat and so many calories you’d only want to eat it if you’re trying to gain weight. As I’ve been saying for years now, calories listed in tables are ballpark numbers. Note that NutritionData continues to list calories and fat in raw peanuts the same as in roasted peanuts:

This is very interesting news and so useful to know. I’ll be looking up and reading the book you mention as well. For some reason, even though I usually buy raw nuts, I thought peanuts should be roasted. Will give the raw ones a try. Guess they’re really legumes though aren’t they? No matter–love peanuts (and legumes)!